Agricultural combines typically have a rotary threshing or separating system for separating grain from larger elements of harvested crops, such as straw, stalks and the like. The grain and smaller elements of crop material, which can include, for instance, pod or cob fragments, typically fall from the separating system directly onto a vibratory cleaning system disposed therebelow, or, onto one or more conveyors for conveyance to the cleaning system. Reference Van Buskirk, U.S. Pat. No. 3,537,460 issued to International Harvester Company; and also Hall et al., U.S. Pat. No. 4,884,994 issued to Deere and Company, both of which illustrate well known internal combine conveyor systems.
The cleaning system typically includes sieves or shoes which are reciprocally moved, usually in the fore and aft directions, for cleaning or sifting the grain from tailings and material other than grain (MOG). Clean grain falling through the sieves drops onto one or more clean grain pans disposed therebelow, which pan or pans are typically inclined downwardly toward a sidewardly extending clean grain auger conveyor. The clean grain auger conveyor receives the clean grain and delivers it to an elevator which carries the clean grain up to a clean grain tank.
During the vibration of the sieves, air is blown upwardly and rearwardly therethrough, so as to carry lighter elements of the MOG, or chaff, away. Heavier elements and tailings too large to fall through the sieves and too heavy to be blown away are carried by the vibrations rearwardly along the surfaces of the sieves so as to fall over the rear edges thereof, onto a tailings pan located below the rear edges. The tailings pan is located below the clean grain pan and is similarly inclined downwardly and forwardly, and extends to a sidewardly extending tailings auger conveyor, which carries the tailings to a tailings return conveyor operable for carrying the tailings upwardly, back to the cleaning or separating system of the combine, for reprocessing.
To facilitate material flow along the clean grain pan and the tailings pan, in some combine models, those pans are connected to at least one of the sieves, so as to be correspondingly vibrated therewith. A problem that has arisen, however, with this arrangement, is that it is a burden on the drive which vibrates this assembly, so as to cause premature wear and failure of the drive. This arrangement is also costly and complex.
Therefore, what is sought is a conveyor arrangement for clean grain and tailings handling in a combine, which overcomes one or more of the problems set forth above.